Preliminary note of the vocal repertoire of a resident population of common bottlenose dolphins, Tursiops truncates in Chile

Abstract

Acoustic records were made from the sailboat "Leviathan II", in the area southwest of the "Choros" coastal island in the central-north of Chile, to test the feasibility of developing studies on the underwater sound production of the resident pod of bottlenose dolphins, Tursiops truncatus. While drifting and having the dolphins under visual contact, the recordings were made using the Ca20 wired hydrophone. A preliminary vocal repertoire was assessed to base further studies. The use of protocols for approaching the dolphins, register and analyze the information resulted in 296 whistles individualized by their spectrographic signal and general acoustic characteristics using the SDP software SpectraLAB-plus. The frequency and duration ranges, were 86.13 Hz to 17323.08 Hz. and from 0.01 to 7.96 sec. 67.5% of the signals were distributed in a steno- band [119 Hz to 4214 Hz; ? 4096 Hz] while 32.5% of the signals were distributed in a broader bandwidth [5222 Hz to 15558 Hz; ? 10336 Hz]. The reason that the in between bandwith was not used, is unknown. The rate to obtain new vocalizations was 0.99 per minute. We developed an effort marker based on the efficiency of the method to obtain identifiable signals as a replacement of the effort measurement through the register time. We estimated the obtained preliminary vocal repertoire, to be an initial step in relation to the vocal diversity potential of this dolphin pod, based on the effort estimate and the low occurrence of repetitions of known vocalizations